18th Edition requirements for surge protection
The arrival of the 18th Edition of the IET Wiring Regulations further reshapes the regulatory landscape for electrical contractors. A number of important areas have been scrutinised and reviewed; among them is the issue of surge protection and devices designed to mitigate any excess voltage risks. Surge protection devices (SPDs) are designed to prevent electric shock and having excess voltage damaging the installation’s wiring infrastructure. Should an over-voltage event occur, the SPD diverts the resulting excess current flow to Earth.
Regulation 443.4 requires, (except for single dwelling units where the total value of the installation and equipment therein does not justify such protection), that protection against transient over-voltages is provided where the consequence caused by over-voltage could result in serious injury, damage to culturally sensitive places, interruption of supply or affect large numbers of co-located persons or loss of life.
When should surge protection be fitted?
For all other installations a risk assessment should be carried out to determine whether SPDs should be installed. Where a risk assessment is not carried out, then SPDs should be installed. Electrical installations in single dwelling units are not required to have SPDs installed, but their use is not precluded and it may be that in discussion with a client such devices are installed, reducing significantly risks associated with transient over-voltages.
This is something contractors have not previously had to consider to any great extent, and will need to be taken account of, both in terms of time allocation for project completion as well as cost add-ons for the customer. Any electronic equipment may be vulnerable to transient over-voltages, which can be caused by lightning activity or a switching event. This creates a voltage spike increasing the wave’s magnitude to potentially several thousand volts. This could cause expensive and instant damage or significantly reduce an item of equipment’s lifespan.
The need for SPDs will depend on many differing factors. These include the level of exposure of a building to lightning-induced voltage transients, the sensitivity and value of the equipment, the type of equipment used within the installation, and whether there is equipment within the installation that could generate voltage transients. While the shift in responsibility of risk assessment falling on the contractor is likely to be a surprise to many, by accessing the correct support they can seamlessly integrate this function into their traditional work approach and ensure adherence to the new regulations.